JP2007254541A - Polyester-based resin composition-processing aid and polyester-based resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester-based resin composition-processing aid which can improve the moldability of polyester-based resins, and to provide a polyester-based resin composition. <P>SOLUTION: This polyester-based resin composition-processing aid comprises an acrylic copolymer having a mass-average mol.wt. of 510,000 to 5,000,000 and containing a reactive group-containing monomer component in an amount of 0.1 to 10 mass% based on all monomer components constituting the acrylic copolymer, and, a polyester-based resin composition containing the same. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a processing aid for a polyester-based resin composition and a polyester-based resin composition using the same.

  Polyester resins, especially polybutylene terephthalate (hereinafter sometimes abbreviated as PBT) are excellent in mechanical, electrical, chemical, and physical properties, and are therefore widely used in automobiles, OA equipment, and the like. Yes. In addition, the use of polylactic acid is spreading as a more environmentally friendly polyester resin.

In general, in blow molding and vacuum molding, which are molding methods with stretching deformation, the stretch characteristics of the resin composition that is the material are directly related to the quality of the molded product, but the influence of a small amount of high molecular weight components on the stretch characteristics Has been pointed out.
For example, in the following Non-Patent Document 1, the relationship between a high molecular weight component and uniaxial extensional flow is clarified. That is, it has been shown that the addition of a high molecular weight component exhibits strain hardening and improves thermoformability.

Various methods have been tried to solve the moldability of the polyester resin.
For example, Patent Document 1 below proposes a method for improving the moldability of a polyester resin by blending a reactive compound having a mass average molecular weight of 200 to 500,000. In this method, it is considered that improvement in moldability is attempted by forming a high molecular weight component in the polyester resin due to the chain extension effect of the reactive compound.
Patent Document 2 below describes a method of molding a foam using a resin composition in which an acrylic processing aid and a foaming agent having a molecular weight of 500,000 to 5,000,000 are added to a polyester resin. . In this method, it is considered that improvement of moldability is attempted using an acrylic processing aid as a high molecular weight component.
Journal of Japanese Society of Rheology Vol. No. 28 3 p. 99-103 JP 2003-238777 A JP 2003-3000 A

However, in the method of Patent Document 1, if the reaction between the reactive compound and the polyester component is not sufficiently controlled, there is a fear that the melt viscosity becomes too high, and there remains an industrial problem.
In the method of Patent Document 2, the dispersibility of the acrylic processing aid may be insufficient, and it is necessary to pay attention to manufacturing conditions such as kneading conditions in order to sufficiently disperse the processing aid. Moreover, although patent document 2 has description about a reactive group containing monomer component, there is no Example and it is not clarified about the peculiar effect.

  This invention is made | formed in view of the said situation, and it aims at providing the processing aid for polyester resin compositions and polyester resin composition which can improve the moldability of polyester resin.

As a result of intensive studies to solve the above problems, the present inventors have invented the following processing aids for polyester resin compositions and polyester resin compositions.
The processing aid for a polyester resin composition of the present invention is an acrylic copolymer having a mass average molecular weight of 510,000 to 5,000,000, and a monomer component containing a reactive group is added to the acrylic copolymer. It is characterized by comprising an acrylic copolymer containing 0.1% by mass or more and 10% by mass or less with respect to all monomer components constituting the coalescence.
The polyester resin composition of the present invention is characterized by containing a polyester resin and the processing aid according to claim 1.

According to the processing aid for a polyester resin composition of the present invention, the moldability of the polyester resin can be improved by adding it to the polyester resin.
The polyester resin composition of the present invention is excellent in moldability and can be molded to produce a high-quality molded product.

<Processing aid for polyester resin composition>
The processing aid for a polyester resin composition of the present invention (hereinafter sometimes simply referred to as a processing aid) is composed of an acrylic copolymer. By using the processing aid, in the molding of the polyester resin composition, the extensional viscosity can be improved while the increase in shear viscosity is small.
The acrylic copolymer is (meth) acrylic acid ester (excluding those included in the following “monomer component containing a reactive group”) in which 51% by mass or more of all monomer components is included. It refers to a certain copolymer. (Meth) acrylic acid means one or both of methacrylic acid and acrylic acid.
In this invention, the more preferable content rate of the said (meth) acrylic acid ester is 70 mass% or more, More preferably, it is 90 mass% or more, and an upper limit is 99.9 mass%.

  Examples of the (meth) acrylic acid ester include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, dodecyl acrylate, octadecyl acrylate, phenyl acrylate, Acrylic esters such as benzyl acrylate; methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, phenyl methacrylate, Methacrylic acid esters such as Gilles methacrylate. These are used alone or in combination of two or more. As the (meth) acrylic acid ester, methyl methacrylate is particularly preferable.

The monomer component constituting the acrylic copolymer in the present invention includes a monomer component containing a reactive group.
Examples of the reactive group of the monomer component containing a reactive group include an amino group, a carboxyl group, an epoxy group, and a hydroxyl group.
Examples of the monomer component having an amino group include diethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, and aminostyrene.
Examples of the monomer component having a carboxyl group include unsaturated acids such as methacrylic acid and acrylic acid, and unsaturated acid anhydrides such as maleic anhydride, itaconic anhydride, and citraconic anhydride.
A glycidyl group is mentioned as an example of an epoxy group. Examples of the monomer component having a glycidyl group include glycidyl methacrylate.
Examples of the monomer component having a hydroxyl group include hydroxyethyl methacrylate and hydroxypropyl methacrylate.
These are used alone or in combination of two or more. As the monomer component containing a reactive group, those having an epoxy group are preferable, and glycidyl methacrylate is particularly preferable from the viewpoint of excellent reactivity with respect to polyester.
The ratio of the monomer component containing the reactive group is 0.1% by mass or more and 10% by mass or less, preferably 1% by mass or more and 5% by mass, out of all monomer components constituting the acrylic copolymer. It is below mass%. When there are too few monomer components containing a reactive group, there exists a possibility that the dispersibility in a polyester-type resin may be inferior. Moreover, when there are too many reactive groups, there exists a possibility that the shear viscosity of a polyester-type resin may raise remarkably and a moldability may fall.

In addition to the above (meth) acrylic acid ester and the above “monomer component containing a reactive group”, the monomer component constituting the acrylic copolymer includes other vinyl monomers not included in these. The monomer may be copolymerized within a range of less than 48.9% by mass. Examples of such other vinyl monomers include aromatic vinyl compounds, vinyl cyanide compounds, and other copolymerizable vinyl monomers.
Examples of the aromatic vinyl compound include styrene, t-butylstyrene, α-methylstyrene, p-methylstyrene, divinylbenzene, 1,1-diphenylstyrene, N, N-diethyl-p-aminoethylstyrene, N, N-diethyl-p-aminoethylstyrene, vinylpyridine, vinylxylene, monochlorostyrene, dichlorostyrene, monobromostyrene, fluorostyrene, ethylstyrene, vinylnaphthalene and the like can be mentioned. As the aromatic vinyl compound, styrene and α-methylstyrene are particularly preferable.
Examples of the vinyl cyanide compound include acrylonitrile and methacrylonitrile. As the vinyl cyanide compound, acrylonitrile is particularly preferable.
Examples of other copolymerizable vinyl monomers include maleimides such as maleimide, N-methylmaleimide, N-butylmaleimide, N- (p-methylphenyl) maleimide, N-phenylmaleimide, and N-cyclohexylmaleimide. Compound etc. are mentioned. The maleimide compound includes, for example, a copolymer obtained by copolymerizing maleic anhydride and imidizing it with aniline or the like.
The above vinyl monomers can be used alone or in combination of two or more.

In the present invention, the acrylic copolymer has a mass average molecular weight of 510,000 to 5,000,000. The mass average molecular weight in the present invention is a polystyrene standard value by gel permeation chromatography.
If the mass average molecular weight is too low, the processability may not be improved until the reactive group and the polyester are sufficiently reacted. If the mass average molecular weight is too high, the dispersibility in the polyester resin may be reduced. May be inferior. A more preferable range of the mass average molecular weight is 1 million or more and 4 million or less.

  The acrylic copolymer can be produced by a polymerization method such as emulsion polymerization, soap-free emulsion polymerization, dispersion polymerization, suspension polymerization, bulk polymerization, or solution polymerization. Emulsion polymerization or soap-free emulsion polymerization is suitably used, and by using these polymerization methods, a processing aid having a mass average molecular weight sufficiently controlled and excellent in dispersibility can be obtained. In particular, emulsion polymerization is preferred.

Specifically, emulsion polymerization for obtaining an acrylic copolymer is carried out by adding a vinyl monomer mixture mainly composed of an acrylic monomer, a polymerization initiator, an emulsifier, and a chain transfer agent if necessary. Usually, it is carried out by heating to 5 to 98 ° C. with stirring.
As a polymerization initiator, redox by combining organic hydroperoxides such as cumene hydroperoxide, diisopropylbenzene hydroperoxide, paramentane hydroperoxide, and reducing agents such as sugar-containing pyrophosphate prescription and sulfoxylate prescription. System polymerization initiators or peroxides such as persulfate, azobisisobutyronitrile, benzoyl peroxide are used.
Chain transfer agents include mercaptans such as n-hexyl mercaptan, n-octyl mercaptan, t-octyl mercaptan, t-dodecyl mercaptan, n-dodecyl mercaptan, n-stearyl mercaptan; chloroform, bromoform, carbon tetrachloride, tetraodor Hydrocarbons such as carbonized carbon; xanthogens such as dimethylxanthogen disulfide and diisopropylxanthogen disulfide; α-methylstyrene dimer, 9,10-dihydroanthracene, 1,4-cyclohexadiene, 1,4-hexadiene, 2, 5-dihydrofuran etc. are mentioned.
As the emulsifier, commonly used emulsifiers can be used. Sodium or potassium salts of fatty acids such as rosin acid, oleic acid, lauric acid, stearic acid, alkenyl succinic acid, alkylallyl sulfonates such as sodium dodecylbenzene sulfonate, Anionic surfactants such as dialkylsulfosuccinic acid are preferred.
As the emulsion polymerization method, generally known emulsion polymerization methods such as batch addition polymerization of monomers, continuous addition polymerization of monomers, multi-stage polymerization, etc. can be adopted, such as emulsifiers, polymerization initiators, chain transfer. The agent can be added in the same manner as the monomer.

<Polyester resin composition>
The polyester resin composition of the present invention contains a polyester resin and a processing aid comprising the above acrylic copolymer.
The polyester resin is not particularly limited, and commercially available polyester resins can be widely applied. For example, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polylactic acid (PLA), and the like.

0.5-10 mass% is preferable and, as for content of the processing aid which consists of the said acrylic copolymer in the polyester-type resin composition of this invention, 1-5 mass% is more preferable. When the amount of the processing aid is too small, the improvement of processability becomes insufficient. When the amount is too large, the physical properties of the polyester resin, for example, the physical properties such as strength may be adversely affected.
In addition, the polyester resin composition of the present invention includes an impact resistance enhancer, an antioxidant, an ultraviolet absorber, an antistatic agent, a lubricant, a foaming agent, a difficult agent, and the like as long as the effects of the present invention are not impaired. Other components such as a flame retardant, an antibacterial agent, a nucleating agent, an antifogging agent and a colorant may be added.

  As a method for producing the polyester resin composition, a method of melt kneading by adding the above processing aid and, if necessary, other components to the polyester resin is suitable. As the melt-kneading method, for example, a known method using a twin screw extruder, a single screw extruder, a roll, a Brabender or the like can be used. In particular, the method using a twin screw extruder is industrially advantageous.

According to this invention, the moldability of this resin composition can be improved by making the polyester-type resin composition contain the processing aid of this invention which consists of the said specific acrylic copolymer. In particular, since the processing aid of the present invention is excellent in dispersibility in a polyester resin, a polyester resin composition excellent in moldability can be easily obtained. Specifically, the extensional viscosity can be improved while suppressing an increase in the shear viscosity of the polyester resin composition.
At the time of molding, it is advantageous that the shear viscosity is low and the extensional viscosity is high. Specifically, the lower the shear viscosity, the better the fluidity at the time of molding. Therefore, even when a more complicated mold or a thin mold is used, molding is easy. In addition, the higher the extension viscosity, the better the stability during molding.

  The extensional viscosity is the viscosity of the resin composition in the extensional flow state, and can be measured by, for example, a Meisner type extensional viscometer. As what is marketed, TAME's RME or TA Instruments' ARES is attached to an extensional vision fixture. With these viscometers, the viscosity at a constant strain rate is measured, and the extensional viscosity is evaluated. Since the evaluation conditions differ depending on the polyester resin used as the matrix resin, the absolute value cannot be discussed. However, the resin after the processing aid is added to the state before the processing aid is added (for example, the matrix resin alone). The elongational viscosity of the composition is preferably 20% or more, more preferably 50% or more.

The shear viscosity is a viscosity at a constant shear rate in the melt flow state of the resin, and a rotary type or a capillary type can be used as a measuring device. As the rotary type, ARES manufactured by TA Instruments and the like are commercially available, and as the capillary type, RH-7 manufactured by Rosand and Capillograph manufactured by Toyo Seiki Co., Ltd. are commercially available. For example, when molding is performed in a high-speed shear region such as injection molding, it is preferable to measure the shear viscosity with a capillary type.
The amount of change in the shear viscosity after the addition of the processing aid is 20% or less with respect to the shear viscosity before the processing aid is added (for example, the matrix resin alone). Is preferable.

  The method for molding the polyester resin composition of the present invention is not particularly limited, but is particularly suitable for methods in which good moldability is desired, such as profile extrusion molding, blow molding, vacuum molding, injection molding, foam molding, etc. It is particularly suitable for profile extrusion molding and blow molding.

In the following Examples and Comparative Examples, “part” is “part by mass” and “%” is “mass%” unless otherwise specified.
<Evaluation items and evaluation methods>
Evaluation items and evaluation methods in the following Examples and Comparative Examples were performed by the following methods.
(1) Dispersion solid content concentration:
The solid content concentration of the polymer dispersion obtained in the process of producing the processing aid was determined by drying the dispersion at 180 ° C. for 30 minutes.
(2) Mass average molecular weight:
In gel permeation chromatography (manufactured by Shimadzu Corporation, LC-10A system), measurement was performed using a column (manufactured by Showa Denko KK, K-806L).
(3) Extension viscosity:
Measurement was performed using ARES-EVF (product name) manufactured by TA Instruments. The measurement conditions were 230 ° C., strain rate 0.1 (1 / s), and the extensional viscosity at the time of 0.1 (s) and 1 (s) was used as an evaluation index.
A sample for measurement was obtained by pressing a resin composition to be measured at 240 ° C. to obtain a film having a thickness of about 0.2 mm, and then cutting it to a width of 10 mm and a length of 18 mm.
(4) Shear viscosity:
This was performed using a capillary rheometer RH7 (product name) manufactured by Rosand. The measurement conditions were 250 ° C. and L / D = 16/1, and the measured values at shear rates of 100 (1 / s) and 1000 (1 / s) were used as evaluation indexes.

[Example 1: Production of acrylic copolymer (X-1) as a processing aid]
An acrylic copolymer was synthesized with the monomer component composition (unit: mass%) shown in Table 1 below.
That is, 290 parts of distilled water, 1 part of dipotassium alkenyl succinate (product name “Latemul ASK” manufactured by Kao Corporation) as an emulsifier, 77 parts of methyl methacrylate (MMA), 20 parts of butyl acrylate (BA), and methacrylic acid 3 parts of glycidyl acid (GMA) was charged into a separable flask equipped with a stirring blade, a condenser, a thermocouple, and a nitrogen inlet, and heated to 60 ° C. under a nitrogen stream. Subsequently, what melt | dissolved 0.2 part of potassium persulfate in 10 parts of distilled water was added, and radical polymerization was started. After the heat generation was completed, the temperature in the system was maintained at 60 ° C. for 1 hour to obtain a polymer (A-1) dispersion. The solid content concentration of this dispersion was 25%.
Subsequently, 400 parts of an aqueous calcium acetate solution having a concentration of 1% by mass was heated and stirred at 80 ° C., and while maintaining the temperature, 300 parts of the polymer (A-1) dispersion obtained above (100 parts as the polymer content) Was gradually added dropwise to solidify and precipitate the solid to form a slurry. Then, the temperature of the slurry was raised to 95 ° C. and solidified. Finally, the precipitate was separated, filtered, and dried to obtain 100 parts of a powdery acrylic copolymer (X-1) as a processing aid. The obtained acrylic copolymer (X-1) had a mass average molecular weight of 3 million.

[Comparative Example 1: Production of acrylic copolymer (X-2)]
An acrylic copolymer as a comparative example was synthesized with the monomer component composition (unit: mass%) shown in Table 1 below.
That is, in Example 1 above, except that 77 parts of methyl methacrylate and 3 parts of glycidyl methacrylate were used instead of 80 parts of methyl methacrylate, the same procedure as in Example 1 was carried out to obtain a powdery form as a comparative example. An acrylic copolymer (X-2) was obtained. The obtained acrylic copolymer (X-2) had a mass average molecular weight of 3.5 million.

[Example 2: Production of polyester resin composition]
A polyester-based resin composition was manufactured using PBT (manufactured by Wintech Polymer Co., Ltd., product name: DURANEX 2002) as the polyester-based resin.
That is, 100 parts of PBT and 3 parts of the processing aid composed of the acrylic copolymer (X-1) obtained in Example 1 were used using a twin-screw extruder (manufactured by Nippon Steel Co., Ltd., product name: TEX-30α). And kneaded at 250 ° C. to obtain a polyester resin composition (Y-1).
Table 2 shows the measurement results of the extensional viscosity and shear viscosity of the obtained polyester resin composition (Y-1). The composition of the polyester resin composition is also shown in Table 2 (the same applies hereinafter).

[Comparative Example 2: Production of polyester-based resin composition]
The polyester resin composition was carried out in the same manner as in Example 2 except that the acrylic copolymer (X-2) obtained in Comparative Example 1 was used instead of the acrylic copolymer (X-1). A product (Y-2) was obtained.

[Comparative Example 3: Production of polyester resin composition]
Except that the acrylic copolymer (X-1) was not used, the same procedure as in Example 2 was performed to obtain a polyester resin composition (Y-3). That is, although it is a polyester-based resin containing no processing aid, in order to give the same heat history as in Example 2, extrusion was performed by a twin screw extruder in the same manner as in melt kneading in Example 2.

As is clear from the comparison between Example 2 and Comparative Example 3 from the results in Table 2, the addition of the processing aid (X-1) of the present invention greatly increases the extensional viscosity of the polyester-based resin, resulting in shearing. An increase in viscosity was satisfactorily suppressed, and a polyester resin composition excellent in moldability was obtained.
On the other hand, as is clear from the comparison between Comparative Example 2 and Comparative Example 3, an acrylic copolymer containing no “monomer component containing a reactive group” is used instead of the processing aid (X-1) of the present invention. In Comparative Example 2 using the polymer (X-2), the elongation viscosity and shear viscosity of the polyester-based resin were not significantly changed as compared with Comparative Example 3 in which only the matrix resin was not added, and the moldability was improved. There is no big difference.

Claims (2)

  An acrylic copolymer having a mass average molecular weight of 510,000 to 5,000,000, wherein a monomer component containing a reactive group is added to the total monomer component constituting the acrylic copolymer in an amount of 0.001. A processing aid for a polyester-based resin composition, comprising an acrylic copolymer that is contained in an amount of 1 to 10% by mass. A polyester resin composition comprising a polyester resin and the processing aid according to claim 1.